Children to Prince Harry and Meghan, Archie and Lilibet have been named prince and princess after the Queen’s passing. This change is possible due to a century-old convention set by King George V in 1917, that the grandchildren of the monarch automatically receive royal titles.
According to CBS NEWS, when Archie was born he was given the honorific title Earl of Dumbarton. He could have had the title of lord, rather his parents opted for him to be called Master Archie.
Archie and Lilibet, grandchildren to King Charles III now have the right to be His Royal Highness Prince Archie of Sussex and Her Royal Highness Princess Lilibet of Sussex whereas they did not immediately qualify as the great-grandchildren of Queen Elizabeth II.
Other family members have also had their titles change after the death of the Queen. Charles is now King of the United Kingdom of Great Britain and Northern Ireland and will be referred to as, “His Majesty” rather than “His Royal Highness.